AUSTIN, Texas (AP) -- Jordan Spieth lost in the fourth round at the Dell Match Play. Then, he lost his No. 1 ranking.
Jason Day assured a return to the top of the ranking when he beat Brooks Koepka to advance to the semifinals. Next up for Day is Rory McIlroy, who overwhelmed Chris Kirk on the back nine at Austin Country Club to run his unbeaten streak in this tournament to 12.
The other semifinal match was still to be determined.
Louis Oosthuizen took the lead on the fourth hole and never trailed against Spieth.